Method evaluate_etc1_error

engine/dlib/src/basis/encoder/basisu_etc.cpp:727–753

	}
		
	uint64_t etc_block::evaluate_etc1_error(const color_rgba* pBlock_pixels, bool perceptual, int subblock_index) const
	{
		color_rgba unpacked_block[16];

		unpack_etc1(*this, unpacked_block);

		uint64_t total_error = 0;

		if (subblock_index < 0)
		{
			for (uint32_t i = 0; i < 16; i++)
				total_error += color_distance(perceptual, pBlock_pixels[i], unpacked_block[i], false);
		}
		else
		{
			const bool flip_bit = get_flip_bit();

			for (uint32_t i = 0; i < 8; i++)
			{
				const uint32_t idx = g_etc1_pixel_indices[flip_bit][subblock_index][i];

				total_error += color_distance(perceptual, pBlock_pixels[idx], unpacked_block[idx], false);
			}
		}

		return total_error;
	}

	void etc_block::get_subblock_pixels(color_rgba* pPixels, int subblock_index) const
	{